Patent GB-537232-A (GB)
Title: Improvements in or relating to photographic films
IPC: G03C1/805
Filed: 1939-12-09
Abstract: 537,232. Photographic stripping materials. DU PONT FILM MANUFACTURING CORPORATION. Dec. 9, 1939, No. 31893. Convention date, Dec. 12, 1938. [Class 98 (ii)] A light-sensitive photographic material comprises a light-sensitive layer joined to a support by an adhesive layer comprising a polymeric nitrogeneous substance containing an amino group or groups which layer is soluble in aqueous acetic acid of 2 to 5 per cent. concentration preferably in 2 per cent. aqueous acetic acid solution but is insoluble in water and 5 per cent. aqueous ammonia. The light-sensitive layer may be a silver halide emulsion or a bichromated gelatine layer. Polymeric nitrogeneous substances referred to are deacetylated chitin; piperidylmethylzein; dicyclohexylaminoethyl methacrylate ; piperidyl-N-ethyl methacrylate; the acid-soluble reaction products of proteins with carbonyl compounds such as lower aliphatic aldehydes and ketones and amines having less than nine carbon atoms in which the amino nitrogen is joined to the aliphatic carbon; the aminocelluloses soluble in dilute acid and containing an amino-nitrogen removed from the cellulose nucleus by the chain of atoms comprising at least one carbon atom ; cellulose amines soluble in stoichiometrical amount of 5 per cent. aqueous acetic acid containing directly attached to the cellulose nucleus from 0.5 to 1.5 amino-nitrogen atoms attached to nuclear carbon atoms per glucose unit; reaction products of vinyl ketone polymers with amino compounds ; products obtained by treating resins having ketone groups with an excess of ammonia or amines and hydrogenating the resulting mixture catalytically at superatmospheric pressure and temperature ; polymeric aminoalcohol esters of acrylic and substituted acrylic acids; and the polymeric alcoholmethacrylates. The substances may be used singly or in combination. The stripping time may be varied by (a) incorporating water-soluble colloids such as glue, dextrine, polyvinyl alcohol, or polymerized methacrylamide ; (b) varying the acid concentration in preparing the solution for making the stripping layer ; (c) varying the concentration of acid in the processing solutions ; (d) hardening with protein hardeners either in the emulsion or a processing bath ; and (e) varying the concentration of polymeric nitrogeneous substance. In an example, paper is coated with baryta, a solution containing deacetylated chitin, lactic acid, ethyl alcohol, and water, a nitrocellulose solution containing also glycerol, urea, dibutyl phthalate, and methyl alcohol, a substratum layer containing gelatine, acetic acid, and ethyl alcohol, and a silver halide gelatine emulsion which may contain optical or gelatine sensitizers. The exposed emulsion may be developed in metolhydroquinone developer, or if rapid stripping is desired, a lactic acid-amidol developer. After washing and fixing in an acid fixing bath the emulsion layer and nitrocellulose support is stripped and transferred to another support where it can be toned or coloured and then transferred to a final support. An acid stop bath may be used after development to effect quicker stripping. The emulsion layer may contain colour formers as described in Specifications 497,463, 512,542 and 14656/39 (as open to inspection under Sect. 91). One emulsion may contain a yellow colour former, another a magenta colour former, and a third a blue-green former. After printing under appropriate colour separation negatives, developing, fixing, stripping, bleaching in ammoniacal potassium ferricyanide, washing, colour developing, washing, removing the silver with Farmer's reducer, and washing, the films are transferred to a permanent transparent or white support. The films may also contain dyes such as Metanil Yellow, Pontamine Fast Scarlet 4BA, and a mixture of Pontamine Sky Blue 6BX and Pontamine Green BX and the dye-destruction bath may be an aqueous solution of stannous chloride and potassium bromide. The stripped films are transferred in register to the final support. In another example, an organic cellulose derivative support carries a gelatine substratum, a stripping layer including piperidylmethylzein, and a gelatine silver halide emulsion containing chrome alum. After exposure, if desired through a half-tone screen, development, and fixing in an acid bath, the picture layer is stripped, washed, and transferred to the final support. In a further example, a negative made through a half-tone screen is printed through the transparent base of the stripping film and the material is developed in a hardening developer and after fixing is transferred to a waxed temporary support. The unhardened gelatine is washed out with warm water, and is transferred to silk bolting cloth screen. The gelatine may also be insolubilized by the bleachhardening process. In a further example, a multilayer stripping film comprises a cellulose acetate base having thin nitrocellulose layers and backed by an anti-halation layer. On one side is a gelatine substratum, a red-sensitized silver halide emulsion, a delayed stripping layer containing deacetylated chitin and glycollic acid, an orthochromatic emulsion, a rapid stripping layer containing deacetylated chitin and lactic acid, and a blue-sensitive emulsion containing a removable yellow filter layer and chrome alum. After exposure, development and fixing, the film is passed through an acetic acid stop bath before fixation. The blue component layer is stripped, transferred to a permanent, transparent support, and fixed. After fixation, the green component layer is stripped and transferred. The red component layer remains on the original support. After washing and drying, threecolour component records are obtained. In another example, an alkali-stripping layer is provided between the top blue-sensitive and middle green-sensitive layers, and an acidstripping layer containing piperidylmethylzein, chrome alum, and sulphamic acid. The ethylcellulose films are coated over the stripping layers. The red-sensitive layer contains colour former resorcinol mono-octadecyl or other higher mono-alkyl ether, the green-sensitive layer a bis-pyrazolone, and the blue-sensitive layer an acylacetoaminoarylmorpholine. The blue-component film is stripped after development. A sulphamic acid-potassium dichromate reversal bath may be employed to avoid the use of a cleaning bath. After reversal the film is colour developed. The green-sensitive film is stripped after treatment in an acid stop bath and treated similarly and the red-sensitive layer is similarly processed on its original support. The three films are then registered and re-united. In a further example a bipack has a front element comprising a transparent support, a gelatine substratum, a blue-sensitive emulsion layer containing Tartrazine O, a second gelatine substratum, a stripping layer containing either dicyclohexylaminoethyl methacrylate, or #-piperidyl-N-ethyl-methacrylate, or #-morpholinoethyl methacrylate, a gelatine layer containing Tartrazine O, a greensensitive emulsion layer, and a red filter layer containing Congo Red. The rear element comprises a red-sensitive emulsion layer, a gelatine substratum, and a support. After exposure, the green-sensitive layer is developed in metol-borax-developer, diffusion being prevented by the stripping layer. After washing and drying, the image in this layer is printed on to a suitably sensitized emulsion layer by deep-red or infra-red rays. On re-development with an acid amidol developer the blue-sensitive layer is developed and the green-sensitive layer can be stripped, transferred to a support, fixed and washed. The rear element is treated separately, and a set of three-colour separation negatives is thus obtained. Specifications 475,131, 475,132, [both in Group IV], 489,655, and 495,105 also are referred to.